1. Field of the Invention
The present invention relates to a silicon nitride layer for a light emitting device, light emitting device using the same, and method of forming the silicon nitride layer for the light emitting device, and more specifically, to a silicon nitride layer for a light emitting device, which includes a silicon nitride matrix and silicon nanocrystals formed in the silicon nitride matrix.
2. Description of Related Art
In order to obtain a light emitting effect using silicon as an indirect bandgap semiconductor, it is necessary to provoke a quantum confinement effect due to fine structures (Refer to Light Emission in Silicon: From Physics to Devices, edited by D. J. Lockwood (Academic Press, San Diego, 1998), Chap. 1).
The quantum confinement effect involves forming fine crystalline or amorphous silicon structures having a size of several nm or less (e.g., quantum wells, quantum wires, and quantum dots) using a matrix or barrier formed of a material that has a larger energy gap than bulk silicon. In this case, as the fine structures become smaller, the wavelength of light they emit becomes shorter. Among the examples of the fine structures, the quantum dot nanostructures exhibit a particularly high quantum yield.
In recent years, research for applications of silicon fine structures formed in a silicon oxide matrix to a silicon light emitting device has progressed (Refer to N. Lalic and J. Linnros, J. Lumin. 80, 263 (1999)., S.-H. Choi and R. G. Elliman, Appl. Phys. Len. 75, 968 (1999)). However, the silicon fine structures were obtained by annealing Si-rich silicon oxide at a high temperature of about 1100 ? or higher for about 30 minutes to 2 hours.
The above-described method involves additional processes and takes much time. Also, problems caused by the high-temperature annealing process remain unsolved. For these reasons, it is difficult to directly apply conventional semiconductor processes to the method.
Moreover, in manufacturing a light emitting device using silicon oxide, it is required to form a matrix or barrier to a very small thickness because of a high application voltage.